1. Field of the Invention
The present invention relates to a silent chain in which multiple link plates each having a pair of teeth and pin apertures are interleaved in the longitudinal and lateral directions and interconnected to each other by the connecting pins, and more particularly, to an improvement of the structure of the silent chain to decrease the chordal oscillation.
2. Description of Related Art
Silent chains are used as timing chains for automobiles, motorcycles, and the like. A silent chain is typically comprised of multiple link plates each having a pair of teeth and pin apertures and pivotably connected to each other by the connecting pins inserted into the pin apertures.
During operation of the silent chain, chordal oscillation that generates in the chain span between the driving and driven sprockets is one of the causes of noise occurrences. Therefore, various efforts have been made to reduce such chordal oscillation.
Japanese patent application laying-open publication No. 63-219940 shows a silent chain with two types of leaf springs of different spring rates that are inserted between the adjacent link plates of the guide rows and that are randomly disposed in the longitudinal direction.
In this case, biasing forces generated by the leaf springs and acting between the adjacent link plates in the lateral direction vary randomly in the longitudinal direction. Thereby, bending resistance of the chain span between the driving sprocket and the driven sprocket vary successively. As a result, eigenfrequency of the chain span vary successively and chordal oscillation of the chain span can be decreased.
However, in the prior art silent chain, the biasing forces by the leaf springs act between the adjacent link plates at all times during operation. Therefore, there is a disadvantage that it has a considerable friction loss during operation which causes a decrease in power transmission efficiency of the chain.
The present invention is directed to providing a silent chain that can decrease the chordal oscillation without causing the frictional loss.